This invention relates to a process for removing olefin oxide from a chlorinated solvent containing a minor amount of the same.
Chlorinated lower aliphatic hydrocarbon solvents such as perchloroethylene, trichloroethylene, 1,1,2-trichloroethane, and 1,1,1-trichloroethane are routinely inhibited against decomposition and reaction with metal containers by the incorporation of minor amounts, up to a few percent, of one or more stabilizers or inhibitors. These inhibiting additives are ordinarily compounds having a boiling point similar to that of the solvent and preferably not easily separable from the solvent by water extraction so that the inhibitor content remains relatively constant during the drycleaning, metal-degreasing, or other cleaning operations where such solvents are commonly used. These inhibiting additives include compounds such as nitromethane, dioxane, and alcohols, which chemically are relatively inert, and also more reactive compounds such as olefin oxides, for example, propylene oxide, butylene oxide, glycidol, and cyclohexene oxide which may serve in part at least as acid acceptors. These epoxides may be present in a stabilized solvent in concentrations up to about 5 percent by weight, but lower concentrations of about 0.01-0.5 percent are usually employed.
In some uses of such inhibited solvent compositions, for example, when the solvent is used in a chemical process either as a solvent or as a reactant, the presence of even a very small amount of a reactive impurity may be highly undesirable where it causes contamination of the product, inactivation of a catalyst, or similar harmful result. Vicinal epoxides such as those named above are examples of potentially disadvantageous reactive impurities. It is well known that olefin oxides react readily with water in the presence of a strong acid to form the corresponding diol, but the diol product and the acid catalyst may also be undesirable and not easily separable from the chlorinated solvent.